Method for diagnosing ADHD and related behavioral disorders

ABSTRACT

The invention features methods and systems for the diagnosis of ADHD and related disorders. The methods and systems of the invention can also be used to ascertain how much benefit an individual would derive from a particular therapy.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application claims benefit of U.S. Provisional Application No.60/788,946 filed Apr. 4, 2006, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The invention relates to methods and systems for the diagnosis of ADHDand related disorders.

Alterations in locomotor-activity levels and disturbances inrest-activity rhythms have long been recognized as an integral sign ofmany psychiatric disorders. For example, the hyperactivity of childrenwith Attention-Deficit/Hyperactivity Disorder (ADHD) is most readilydiscernible as a failure to inhibit motor activity to low-levels.

Using precisely quantified movements, ADHD children have been shown tobe 3-4 fold more active than controls. Teicher et al., J. Am. Acad.Child Adolsec. Psychiatry 35:334 (1996). However, the precise nature oftheir hyperactivity is unknown.

There is a need for reliable, inexpensive, and easy to use methods fordiagnosing ADHD and related disorders.

SUMMARY OF THE INVENTION

The invention features methods and systems for the diagnosis of ADHD andrelated disorders. The methods and systems of the invention can also beused to ascertain how much benefit an individual would derive from aparticular therapy.

In a first aspect, the invention features a method of diagnosing adisorder selected from ADHD and related disorders. The method includesthe steps of: (i) using a motion analysis device to record movements ofthe subject; (ii) calculating the power spectral density of theoscillations in the movements; and (iii) on the basis of the spectraldensity, determining whether the subject has the disorder. Desirably,the spectral density is calculated over a frequency range between 0.01and 0.5 Hz, 0.01 and 0.3 Hz, 0.01 and 0.1 Hz, or 0.05 and 0.2 Hz.

The invention features a method of diagnosing a disorder selected fromADHD and related disorders. The method includes the steps of: (i) usinga motion analysis device to record movements of the subject; (ii)calculating the number of spikes in the movements; and (iii) on thebasis of the number, determining whether the subject has the disorder.

The invention also features a method of diagnosing a disorder selectedfrom ADHD and related disorders in a subject. The method includes thesteps of: (i) using a motion analysis device to record movements of thesubject; (ii) calculating the time intervals between spikes in themovements; and (iii) on the basis of the time intervals, determiningwhether the subject has the disorder.

In a related aspect, the invention features a method for assessing theefficacy of a medicament for the treatment of a disorder selected fromADHD and related disorders in a subject diagnosed with the disorder by(a) administering the medicament to the subject; (b) using a motionanalysis device to record movements of the subject while medicated; (c)calculating the power spectral density of the oscillations in themovements; and (d) on the basis of the spectral density, determiningwhether the symptoms of the disorder are ameliorated by the medicament.The method can further include the steps of (e) prior to step (a), usinga motion analysis device to record movements of the subject whileunmedicated; (f) calculating the power spectral density of theoscillations in the movements; and (g) on the basis of the spectraldensity for step (c) and the spectral density for step (f), determiningwhether the symptoms of the disorder are ameliorated by the medicament.

In another aspect, the invention features a method for assessing theefficacy of a medicament for the treatment of a disorder selected fromADHD and related disorders in a subject diagnosed with the disorder by(a) administering the medicament to the subject; (b) using a motionanalysis device to record movements of the subject while medicated; (c)calculating the number of spikes in the movements; and (d) on the basisof the number, determining whether the symptoms of the disorder areameliorated by the medicament. The method can further include the stepsof (e) prior to step (a), using a motion analysis device to recordmovements of the subject while unmedicated; (f) calculating the numberof spikes in the movements; and (g) on the basis of the number for step(c) and the number for step (f), determining whether the symptoms of thedisorder are ameliorated by the medicament.

The invention further features a method for assessing the efficacy of amedicament for the treatment of a disorder selected from ADHD andrelated disorders in a subject diagnosed with the disorder by (a)administering the medicament to the subject; (b) using a motion analysisdevice to record movements of the subject while medicated; (c)calculating the time intervals between spikes in the movements; and (d)on the basis of the time intervals, determining whether the symptoms ofthe disorder are ameliorated by the medicament. The method can furtherinclude the steps of (e) prior to step (a), using a motion analysisdevice to record movements of the subject while unmedicated; (f)calculating the time intervals between spikes in the movements; and (g)on the basis of the time intervals for step (c) and the time intervalsfor step (f), determining whether the symptoms of the disorder areameliorated by the medicament.

In an embodiment of any of the above methods of the invention, themethod further includes continuous performance testing of the subjectwhile recording the movements.

In another embodiment of any of the above methods of the invention, themethod includes measuring the activity of the subject using an infraredmotion analysis system by tracking the movements of the subject's head,leg, elbow, shoulder, hand, or foot using a camera.

In any of the above methods, desirably, the number of spikes or theinterval between spikes is calculated for two or more differentamplitudes.

The invention also features a system for diagnosing a disorder selectedfrom ADHD and related disorders in a subject. The system includes: (i) amotion analysis device; (ii) a device for receiving and storing motiondata; and (iii) a processor provided with a computer program foranalyzing the motion data to calculate the power spectral density of theoscillations.

The invention further features a system for diagnosing a disorderselected from ADHD and related disorders in a subject. The systemincludes: (i) a motion analysis device; (ii) a device for receiving andstoring motion data; and (iii) a processor provided with a computerprogram for analyzing the motion data to calculate the number of spikesin the motion.

The invention features a system for diagnosing a disorder selected fromADHD and related disorders in a subject. The system includes: (i) amotion analysis device; (ii) a device for receiving and storing motiondata; and (iii) a processor provided with a computer program foranalyzing the motion data to calculate the time intervals between spikesin the motion.

In an embodiment of any of the systems of the invention, the motionanalysis device includes a camera for measuring the activity of asubject using infrared light.

In any of the above aspects, a spike threshold can be set at anamplitude of greater than 1 mm/sec, 2 mm/sec, 3 mm/sec, 4 mm/sec, 5mm/sec, 6 mm/sec, 7 mm/sec, or even 8 mm/sec.

In any of the above aspects, the disorder is ADD, ADHD, or HyperkineticDisorder.

As used herein, “ADHD or a related disorder” refers to disorderscharacterized by developmentally inappropriate degrees of inattention,overactivity, and impulsivity, such as Attention Deficit HyperactivityDisorder—combined subtype, Attention Deficit HyperactivityDisorder—predominantly hyperactive-impulsive subtype, Attention DeficitHyperactivity Disorder—predominantly inattentive subtype, AttentionDeficit Disorder with or without hyperactivity, Hyperkinetic Disorder,oppositional defiant disorder and conduct disorder. Attention DeficitHyperactivity Disorder is a disorder characterized by inattention,impulsiveness, and hyperactivity. This disorder can impair socialfunction, learning and/or development and is therefore now recognized asa serious problem. It is further recognized that many children with ADHDgo on to develop other comorbid conditions or social problems inadulthood. In clinical terms ADHD is diagnosed if any one of the threemain clinical features, inattention, over-activity, and impulsiveness,persists in two or more situations, e.g. in both a home and schoolenvironment (American Psychiatric Association. Diagnostic andStatistical Manual of Mental Disorders, Fourth Edition (DSM-IV)Washington D.C.; American Psychiatric Association, 1994). A diagnosis ofHyperkinetic Disorder is made only if all three of the main clinicalfeatures (inattention, over-activity and impulsiveness) have beenpresent from an early age, persist in more than one situation (e.g. homeand school) and impair function (The ICD-10 Classification of Mental andBehavioural Disorders: Diagnostic Criteria for Research. Geneva: WorldHealth Organisation, 1993: 155-7).

As used herein, the term “spike” refers to a burst in the rate ofmovement in a subject that exceeds a threshold amplitude (e.g., 1mm/sec). Spikes can be measured across the test period using anysuitable time scale from milliseconds to minutes, preferably seconds,and amplitudes set to scale from a maximum value in the reference rangeto a suitable minimum of about 2× the baseline. Desirably, the spikeamplitude is in the range of 1 mm/sec to 8 mm/sec (see FIG. 3 forexemplary time series data). The ‘spike’ continues until the movementfalls back below the threshold amplitude level, ending the spike.Optionally, the spike doesn't end unless the movement remains below thethreshold amplitude level for a set minimum amount of time (e.g., 240msec to 1 sec). Such analysis can be accomplished using a variety oftechniques, such as wavelet analysis, or by requiring the spike train toremain below threshold for a minimum time period.

Other features and advantages of the invention will be apparent from thefollowing detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a system for performing a method of the invention. Thesystem includes a motion analysis device 8 that is connected to thecomputer 3 and positioned so as to record the movements of the subject4.

FIG. 2 a is a graph showing that methylphenidate therapy reduces thenumber of spikes exhibited in the motor activity of children with ADHD.See Example 1.

FIG. 2 b is a graph showing that methylphenidate therapy increases theinterspike interval exhibited in the motor activity of children withADHD. See Example 1.

FIG. 3 is a graph showing the rate (mm/sec) of head motor activity of asubject as a function of time. The activity data exhibits briefintermittent high-amplitude spikes.

DETAILED DESCRIPTION

A characteristic signature of ADHD and related disorders has been foundin the movements of subjects suffering from such disorders. Theinvention exploits the relationship between the spectral density ofmultisecond oscillations, number of spikes, and/or the intervals betweenspikes and ADHD to provide methods and system for the diagnosis of ADHDand related disorders. The methods and systems of the invention can alsobe used to ascertain how much benefit an individual would derive from aparticular therapeutic regimen (see Example 1).

Systems

An embodiment of a system for performing a method of the invention isshown in FIG. 1. The system includes a motion analysis device 8 that isconnected to the computer 3 and positioned so as to record the movementsof the subject 4. Any video camera or other motion-sensing devicecapable of detecting the movements of the subject 4 can be used. Forinstance, the motion analysis device 8 can be an infrared motionanalysis system that includes a high-resolution CCD infrared videocamera, an infrared strobe, and a video processor that provides hardwareanalysis of the video signal and outputs data to the computer 3. Suchinfrared motion analysis systems are known in the art, and arespecifically designed to detect and record the precise vertical andhorizontal position of small, light-weight infrared reflective markers9. These markers 9 are attached to the subject 4 at various points, suchas the head, shoulders, and elbows. As the subject 4 moves theseportions of his or her body, the IR motion analysis system detectschanges in the positions of the markers 9 and relays this information tothe computer 3. Successive marker coordinates can be stored in thecomputer 3 and analyzed.

The computer 3 can be a stand-alone personal computer, preferably withhigh computational capacity microprocessors. Alternatively, aminicomputer or mainframe computer can be used. The computer 3 can havea disc drive 6 into which the software that analyzes the subject'sinput's and/or movement patterns is loaded. In a preferred embodiment,the computer 3 has a connection 7 to a network of computers, such as aglobal computer network. This allows the computer 3 to exchange datawith other computers connected to the network. In other preferredembodiments, the computer network is a local area network, a wide areanetwork, an intranet, or an extranet. Thus, a subject may be tested notonly in a clinical setting, but also at a remote location, such as thehome, school, or workplace, thereby eliminating the inconvenience oftraveling long distances for testing.

The system may also include a monitor 1 that is a capable of displayingvisual images on a screen 5. The monitor 1 is attached to a computer 3and is positioned in proximity to a subject 4, so that the subject 4 mayview the images displayed on the monitor screen 5. The computer 3 can beprogrammed to display a desired sequence of images, to which the subject4 is instructed to respond by activating an input device 2 that is alsoattached to the computer 3 and is controllable by the subject 4. Theinput device 2 can be, for example, a standard computer keyboard, ahand-held plunger switch, or a large, easy-to-hit switch several (2-3)inches in length. When activated, the input device 2 sends the subject'sinputs to the computer 3 which stores and analyzes the incidents ofdevice activation.

Motion Detection System

A motion detection system is used to track the movement of the headan/or lower extremities of the individual being tested. Any video cameraor other motion-sensing device capable of detecting the movements of thetest subject can be used. For example, the motion analysis device can bean infrared motion analysis system (e.g., Qualisys, Glastonbury, Conn.)that includes a high-resolution CCD infrared video camera, an infraredstrobe, and a video processor that provides hardware analysis of thevideo signal and outputs data to a computer. Such infrared motionanalysis systems are known in the art, and are specifically designed todetect and record the precise vertical and horizontal position of small,light-weight infrared reflective markers. These markers are attached tothe subject at various points, such as the head, shoulders, arms, legs,and feet. As the subject moves these portions of his or her body, the IRmotion analysis system detects changes in the positions of the markersand relays this information to a computer. Successive marker coordinatescan be stored in the computer and analyzed. Desirably, the camera ispositioned in front of the subject, who is preferably in a seatedposition. The camera is also desirably positioned in such a manner thatit can capture movements of the reflective markers in three dimensions,including movements towards and away from the display device. The motionanalysis device can also include a second camera that can be used incombination with the first camera to better differentiate threedimensional movement. Adults with ADHD or related disorders can manifesthyperactivity solely through excess movement of their lower extremitieswhile seated. Therefore, the first camera can be used to track themovement of the subject's legs and/or feet or a second camera can beused to track the movement of the subject's lower extremities while thefirst camera tracks upper body movements. Alternatively, visible lightand standard video camera are used to measure the movement of a subject,or an accelerometer is used.

Movement patterns can be analyzed using procedures described by Teicheret al., J. Am. Acad. Child Adolsec. Psychiatry 35:334 (1996), which arebased on the concept of microevents. A new microevent begins wheneverthe marker moves more than a predetermined distance from the location ofthe previous microevent, and is defined by its position and duration.

Exemplary data showing the head motion of a subject is provided in FIG.3. First, a threshold amplitude level is set (e.g., 1 mm/sec) and thenumber of spikes in the movements and/or the interval between spikes inthe movements is calculated.

Individuals with ADHD have an increased number of spikes at any selectthreshold, and have a shorter average interspike interval (seeExample 1) in comparison to individuals without ADHD.

Furthermore, the efficacy of a therapeutic regimen can be assessed usingthe methods and systems of the invention. An effective treatment is onewhich reduces the number of spikes, and lengthens the average interspikeinterval across the different threshold values.

Optionally, the methods of the invention are used to create a curve of‘spike’ numbers versus threshold amplitude, which is then compared to anormative database to ascertain whether the individual's profiledeviates significantly from normal subjects. The comparison can be madeusing neural network techniques, or by using a variety of statisticaltechniques, such as logistic regression analysis, cluster analysis,discriminant analysis, or optimal data analysis, to see if theindividuals profile better resembles normal or ADHD.

A variety of statistical techniques can be used in connection with themethods and systems of the invention. For example, the movement timeseries can be analyzed using a mathematical techniques such as FourierTransform, Wigner-Wille Transform, or wavelet analysis to decompose timeseries from time domain into frequency domain. Once converted to thefrequency domain, the amount of spectral power can be calculated for theoscillations in the movements. Desirably, the spectral power iscalculated within a low-frequency (multisecond oscillation) domain(e.g., between 0.01 and 0.5 Hz).

Individuals with ADHD exhibit an increase in the spectral power of thelow frequency motion of the subject in comparison to individuals withoutADHD. Spectral power can also be used to assess the efficacy of atherapeutic regimen. An effective treatment is one which reduces the lowfrequency motion of the subject.

Continuous Performance Test

The subject is, desirably, engaged in a continuous performance test(CPT) while the motor activity of the subject is monitored. For example,subject's visual attention can be tested by displaying a series ofvisual stimuli, to which the subject is instructed to respond.Typically, the stimuli are of two types, and the subject is instructedto respond to only one of them. Data are collected for each stimuluspresented including the type of stimulus, whether or not the subjectresponded, and if so, how long the subject took to respond. Thecontinuous performance attention test has been in use since the mid 50's(Rosvold et al., J. Consulting and Clinical Psychology 20:343 (1956)),with computerized versions available in the 1970's (Greenberg,Psychopharmacol. Bull. 23:279 (1987)).

The CPT results can include measuring errors of commission, errors ofomission, and mean correct reaction time with standard deviation. Moresophisticated CPT measures, derived from signal detection theory caninclude a calculation of stimulus sensitivity (d′) (see, for example,Nuechterlein, J. Abnorm. Psychol. 92:4 (1983)).

Analysis of the CPT results can also include assessing the pattern orfluctuation in attentional states by a subject during a test period.This approach is described in U.S. Pat. No. 6,685,652, incorporatedherein by reference.

The methods of the invention may be used alone, together, or inconjunction with other well-known psychological tests for determiningattention or reaction time. Testing of the subject's performance may beconducted with or without providing corrective feedback to the subjectduring performance of the CPT.

Therapy and Dosing Regimens

The methods and systems of the invention can provide information on theefficacy of any particular therapy in an individual. For example, usingthe methods of the invention it can be possible to determine how asubject would respond to any of the different long acting stimulantpreparations (e.g., Concerta™ 18, 36, and 54 mg; Metadate CD™ 20, 40, 60mg; Ritalin-LA™ 10-60 mg) or combinations, such as Ritalin-LA™ 40 mgtaken at 8 am and Ritalin™ immediate release 15 mg taken at 4 PM. Theseassessments are made based upon the degree of improvement in a subject'smotor activity and, optionally, performance on CPT testing.

If a test subject fails to show substantial benefits on one class ofstimulants (i.e., methylphenidate versus amphetamine derivatives, suchas dextroamphetamine or Adderall), the subject can be tested on aseparate day on a drug from the other class of stimulants. Clinicalresearch has shown that patients with ADHD often respond better to oneclass of stimulants than another, and that a significant number ofpatients with ADHD will have a very beneficial response to one class ofagents but will fail to respond to the other class, or will haveside-effects on only one class (see, for example, Elia et al.,Psychiatry Res. 36:141 (1991)).

The following example is put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how themethods and compounds claimed herein are performed, made, and evaluated,and are intended to be purely exemplary of the invention and are notintended to limit the scope of what the inventors regard as theirinvention.

EXAMPLE 1 Motor Activity in ADHD Children with and withoutMethylphenidate Therapy.

Sixty-two boys (10.6±1.1 years of age, range 9-12) meeting DSM-IVcriteria for ADHD, participated in this IRB-approved study. Headmovements were recorded prior to, and following, a probe dose of 0.4mg/kg methylphenidate, while subjects were seated and performing aGo/No-Go CPT (Teicher et al., J. Child Adolesc. Psychopharmacol.14(2):219-32 (2004)). An infrared motion analysis system tracked andrecorded vertical and horizontal position of a head marker 50 times persecond to a resolution of 1 mm.

ADHD children had episodic bursts of movement, which occurred asdiscrete spikes. Across spike amplitude threshold children with ADHD hadfrom 2× (low threshold)−44× (high threshold) more spikes off medication(MPH effect: F_(1,61)=73.87, p<10⁻¹¹, see FIG. 2 a). Spikes had atypical amplitude of between 1.6-6.4 mm, mean duration of 240 msec, andan interspike interval (ISI) of 10-100 seconds (x=26.0 sec). MPH therapyincreased the interspike interval by 2-4 × (e.g., 2 mm threshold, ISI14.5±23.5 vs. 43.0±56.8 sec, F1,39=8.82, p<0.005, see FIG. 2 b).

Prior to treatment about 25% of the activity of ADHD children occurredas discrete spikes. MPH reduced this by 80% by markedly attenuatingnumber of spikes and increasing interspike intervals.

Other Embodiments

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each independent publication or patent application was specificallyand individually indicated to be incorporated by reference.

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure that come within known or customary practice withinthe art to which the invention pertains and may be applied to theessential features hereinbefore set forth, and follows in the scope ofthe claims.

Other embodiments are within the claims.

1. A method of diagnosing ADHD or a related disorder in a subjectcomprising the steps of: (i) using a motion analysis device to recordmovements of said subject; (ii) calculating the power spectral densityof the oscillations in said movements; and (iii) on the basis of saidspectral density, determining whether said subject has said disorder. 2.The method of claim 1, wherein said spectral density is calculated overa frequency range between 0.01 and 0.5 Hz.
 3. The method of claim 2,wherein said spectral density is calculated over a frequency rangebetween 0.01 and 0.3 Hz.
 4. The method of claim 3, wherein said spectraldensity is calculated over a frequency range between 0.01 and 0.1 Hz. 5.The method of claim 3, wherein said spectral density is calculated overa frequency range between 0.05 and 0.2 Hz.
 6. A method of diagnosingADHD or a related disorder in a subject comprising the steps of: (i)using a motion analysis device to record movements of said subject; (iv)calculating the number of spikes in said movements; and (v) on the basisof said number, determining whether said subject has said disorder.
 7. Amethod of diagnosing ADHD or a related disorder in a subject comprisingthe steps of: (i) using a motion analysis device to record movements ofsaid subject; (ii) calculating the time intervals between spikes in saidmovements; and (iii) on the basis of said time intervals, determiningwhether said subject has said disorder.
 8. The method of claims 6 or 7,wherein said spikes have an amplitude of greater than 1 mm/sec.
 9. Themethod of claim 8, wherein said spikes have an amplitude of greater than3 mm/sec.
 10. The method of claim 6, wherein said number of spikes iscalculated for two or more different amplitudes.
 11. The method ofclaims 1, 6, or 7, wherein said disorder is ADD, ADHD, or HyperkineticDisorder.
 12. The method of claims 1, 6, or 7, further comprisingcontinuous performance testing of said subject while recording saidmovements.
 13. The method of claims 1, 6, or 7, wherein step (i)comprises measuring the activity of said subject using an infraredmotion analysis system by tracking the movements of said subject's head,leg, elbow, shoulder, hand, or foot using a camera.
 14. A method forassessing the efficacy of a medicament for the treatment of ADHD or arelated disorder in a subject diagnosed with said disorder, said methodcomprising: (a) administering said medicament to said subject; (b) usinga motion analysis device to record movements of said subject whilemedicated; (c) calculating the power spectral density of theoscillations in said movements; and (d) on the basis of said spectraldensity, determining whether the symptoms of said disorder areameliorated by said medicament.
 15. The method of claim 14, furthercomprising: (e) prior to step (a), using a motion analysis device torecord movements of said subject while unmedicated; (f) calculating thepower spectral density of the oscillations in said movements; and (g) onthe basis of said spectral density for step (c) and said spectraldensity for step (f), determining whether the symptoms of said disorderare ameliorated by said medicament.
 16. A method for assessing theefficacy of a medicament for the treatment of ADHD or a related disorderin a subject diagnosed with said disorder, said method comprising: (a)administering said medicament to said subject; (b) using a motionanalysis device to record movements of said subject while medicated; (c)calculating the number of spikes in said movements; and (d) on the basisof said number, determining whether the symptoms of said disorder areameliorated by said medicament.
 17. The method of claim 16, furthercomprising: (e) prior to step (a), using a motion analysis device torecord movements of said subject while unmedicated; (f) calculating thenumber of spikes in said movements; and (g) on the basis of said numberfor step (c) and said number for step (f), determining whether thesymptoms of said disorder are ameliorated by said medicament.
 18. Amethod for assessing the efficacy of a medicament for the treatment ofADHD or a related disorder in a subject diagnosed with said disorder,said method comprising: (a) administering said medicament to saidsubject; (b) using a motion analysis device to record movements of saidsubject while medicated; (c) calculating the time intervals betweenspikes in said movements; and (d) on the basis of said time intervals,determining whether the symptoms of said disorder are ameliorated bysaid medicament.
 19. The method of claim 18, further comprising: (e)prior to step (a), using a motion analysis device to record movements ofsaid subject while unmedicated; (f) calculating the time intervalsbetween spikess in said movements; and (g) on the basis of said timeintervals for step (c) and said time intervals for step (f), determiningwhether the symptoms of said disorder are ameliorated by saidmedicament.
 20. A system for diagnosing a disorder selected from ADHDand related disorders in a subject comprising: (i) a motion analysisdevice; (ii) a device for receiving and storing motion data; and (iii) aprocessor provided with a computer program for analyzing said motiondata to calculate the power spectral density of the oscillations in saidmotion.
 21. A system for diagnosing a disorder selected from ADHD andrelated disorders in a subject comprising: (i) a motion analysis device;(ii) a device for receiving and storing motion data; and (iii) aprocessor provided with a computer program for analyzing said motiondata to calculate the number of spikes in said motion.
 22. A system fordiagnosing a disorder selected from ADHD and related disorders in asubject comprising: (i) a motion analysis device; (ii) a device forreceiving and storing motion data; and (iii) a processor provided with acomputer program for analyzing said motion data to calculate the timeintervals between spikes in said motion.
 23. The system of any of claims20-22, wherein said motion analysis device comprises a camera formeasuring the activity of a subject using infrared light.